EXHAUST AFTERTREATMENT SYSTEMS FOR GASOLINE AND ALTERNATIVE-FUELED ENGINES, WITH REDUCTION OF HC, CO, NOx, AND PM

Abstract

An exhaust gas emissions aftertreatment system for spark-ignition engines, which simultaneously reduces the particulate matter, HC, CO, and NOx content of the exhaust. Various embodiments of the system have both a closely-coupled TWC device, and an under-floor treatment device. The under-floor device has either TWC or NOx reduction functionality, depending on whether the engine is run under stiochiometric or lean burn operating conditions.

Description

TECHNICAL FIELD OF THE INVENTION[0001]This invention relates to reducing harmful exhaust emissions from gasoline and alternative-fueled engines, and more particularly to exhaust aftertreatment systems for such engines that address particulate emissions in addition to gaseous emissions.BACKGROUND OF THE INVENTION[0002]Internal combustion engines used for both mobile and stationary applications are subject to strict emission limits. Approaches to reducing emissions include improved in-cylinder combustion designs or fuel modifications, but these improvements have fallen short of meeting emissions limits. Other approaches involve the use of exhaust aftertreatment devices, which have achieved significant emissions reductions.[0003]For diesel engines, particulate matter (PM) emissions are regulated in the United States and other developed nations. However, for spark-ignited engines, currently there are no regulations that address PM emissions. Spark-ignited engines may be either gasoline ...

AI Technical Summary

Problems solved by technology

Approaches to reducing emissions include improved in-cylinder combustion designs or fuel modifications, but these improvements have fallen short of meeting emissions limits.

However, for spark-ignited engines, currently there are no regulations that address PM emissions.

It is generally believed that smaller diameter PM is more harmful to health as it can penetrate more deeply into the lungs.

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